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Truffles, Bottled
Soak the truffles for an hour or two in fresh water, wash them well in several waters, brush them until they are quite clean, and pare them. Put them into wide-mouthed and perfectly dry bottles, and put in each bottle a sprig of thyme, a large pinch of salt, and a table-spoonful of cold water. Cork the bottles closely, and tie them down securely. Wrap a wisp of hay round them to keep them from cracking, put them side by side in a large stewpan, and pour in sufficient cold water to reach up to their necks. Bring the liquor to the boil, then draw the saucepan to the side, and keep it simmering gently for half an hour. Let the bottles remain untouched till they are cold, wax the corks, and store the truffles in a cool place. As English truffles are much cheaper than French ones, it is good economy to bottle them when they are in season for future use. Care should be taken to smell them before bottling, and to reject any that are in the least musty. They are best in December and January. Time to boil the truffles, half an hour.
This is a home-canning method for a low-acid food, and it fails on every count that modern preserving practice measures. The notes below explain why rather than how to fix it.
- The core problem: low acid, no acid addedTruffles sit near pH 6, well above the 4.6 threshold below which Clostridium botulinum cannot grow. The only additions here are salt, thyme and a spoonful of water, none of which acidify the jar or reach a preserving concentration.
- Half an hour of simmering does not steriliseA water bath brings the contents to roughly 100C (212F) at best. Botulinum spores survive that indefinitely; destroying them in a low-acid pack requires pressure canning at around 115-121C for a measured time. The recipe achieves pasteurisation, not sterilisation.
- Sealed, oxygen-free, and stored warmSealed, oxygen-free, and stored without refrigeration -- A corked and waxed bottle kept in a larder is an anaerobic environment, and the book's 'cool place' is not cold enough to be relied on to prevent surviving spores from germinating. The toxin they produce has no smell, taste or visible sign, so the book's advice to reject anything musty offers no protection at all.
- Corks are not a preserving closureCork tied down and dipped in wax cannot be relied on to hold a vacuum or to exclude contamination, and the seal cannot be inspected afterwards the way a modern lid can. The hay wrapping is there only to stop the glass knocking and cracking in the pan.
- Soil-borne spores are the specific hazardTruffles grow underground and are dug out of soil, which is the natural reservoir of botulinum spores. Washing, brushing and paring cannot be guaranteed to remove every trace from a deeply fissured surface; this is a poor candidate for an unpressurised pack.
- Vessels and termsThe 'large stewpan' here is a wide pan of water serving as the bath, big enough to stand the bottles side by side, and 'draw the saucepan to the side' means moving it off the direct heat of a range to hold a bare simmer.
- If you want to keep trufflesFollow a current tested method for preserving fungi, or freeze them; do not adapt this procedure. Fresh truffles are in any case at their best used within days.
Cassell's assumes something a modern British cook would not: that truffles were a local crop worth laying down by the bottle. The English truffle, Tuber aestivum, was gathered from chalk beech woods in Hampshire, Wiltshire and Kent by professional truffle hunters working trained dogs, and it sold well below the price of the Périgord black truffle that French cookery demanded — hence the book's frank appeal to "good economy". The trade is generally traced through the nineteenth century, and professional hunting persisted in Wiltshire into the 1930s before dying out. The whole entry belongs to a period when bottling in a water bath was a common household answer to a glut, decades before the microbiology of low-acid canning was understood.